How many people do you know-right now-who are on a diet?
If you’re like me, then it’s probably a number you can’t count on both hands.
The fact is-despite spending more on our health than ever before-we tend to eat the wrong foods. To make up for this, every once in a while people try the latest crash diet to slim down a bit.
Unfortunately, these diets rarely work, and people often jump from one to another seeking success.
But could this failure be because our body has a protective mechanism that works against crash dieting?
A recent study suggests this may be the case.
What We Know So Far
We have long known that the amount of food we eat affects our basal metabolic rate. For instance, in times of food restriction, our body will compensate by slowing down metabolic processes and burning fewer calories.
This effect occurs to preserve energy, and it is a survival mechanism. In other words, it’s a positive thing that helped many of our ancestors survive harsh famines.
However, times change and rather than starvation, food abundance is now a critical issue facing many developed nations.
The Obesity and Diet Problem
Nowadays, we have hyper-palatable foods for sale on every street, snacks in the office, and vending machines wherever we turn.
People frequently over-indulge, and as a society, we are eating far too much. Of course, this has far-reaching consequences in the area of obesity and long-term chronic disease.
To illustrate the severity of this problem, we only need to look at the statistics. In 2008, nearly 1.5 billion people were either overweight or clinically obese. If you think that sounds a lot, then the future is even scarier; this number is expected to reach a combined 3.28 billion by 2030 (1).
At any rate, health authorities tell us that we can beat obesity by “burning more calories than we consume.”
That is the official line on the issue – one that has been a cornerstone of dietary advice for as long as I remember.
But is the message the right one?
Hormones Are the Key, Not Calories
While this may appear “unconventional”, our hormones have an intricate link to obesity and focusing solely on calories misses the boat, so to speak.
Despite the universal message that calories in vs. calories out is all that matters, there are various metabolic factors in play that determine successful weight loss.
As noted earlier, a recent study appears to suggest that our brain cells can influence the amount of fat we burn.
To explain in more detail, the research investigated a group of neurons in the hypothalamus region of the brain known as agouti-related proteins (AGRP).
These neurons are known to have a significant effect on appetite regulation and hunger cues. For example, when these neurons are ‘switched on’ we experience cravings for food.
Notably, the research showed that when AGRP neurons are ‘off,’ they cause our body to try to preserve energy by dropping our metabolic rate. As a result, the number of calories we burn (and hence weight loss) falls.
In other words, extreme crash dieting causes the rate at which we burn calories to plummet. While this shows that the sole focus on calorie counting is wrong, it doesn’t mean that reducing calories is not good for us.
In fact, if we want to lose weight then we should focus on reducing our food intake. However, unnecessary and continuous food restriction is not the way to do this, as our body will use its protective mechanisms to lower the amount of fat we can burn.
How Can We Lose Weight and Keep Our Metabolic Rate High?
Firstly, it’s important to note that a lower metabolic rate does not mean that we can’t lose weight.
We can see this by looking at the impact of daily caloric restriction and intermittent fasting regimes; both do cause significant weight loss (3).
A lower metabolic rate only means that losing fat will occur at a slightly slower pace.
However, it is certainly possible to achieve weight loss while keeping our metabolic rate high and there are several different ways we can do this.
1. Lower carbohydrate diets
2. Exercise programs
3. Sufficient protein intake
Also, each of these methods has the added benefit of allowing us to enjoy food and not having to starve ourselves with an unnecessary calorie restrictive diet.
1. Lower Carbohydrate Diets
It’s a modern day fact that many of us are eating too much carbohydrate in our daily lives. Refined carbohydrates are particularly harmful, and yet they are prevalent in a vast majority of diets. Perhaps a typical day for some people might look like cereal for breakfast, a donut and soda mid-morning, bread and potato chips for lunch, and pasta dishes for dinner.
This kind of food intake creates blood glucose and insulin spikes and encourages the body to store fat. But what happens when we lower our carbohydrate intake?
Interestingly, low-carbohydrate diets affect weight loss (and our AGRP neurons) in a very different way to extremely low-calorie diets. In short, carb-restriction and starvation have a similar biochemical impact on fat-burning processes, yet they are opposites in how they achieve this.
For example, when we restrict calories to a low level our body will experience a shortage in glucose. How does it react? By pulling (converting) the required glucose from the body’s muscle stores.
Of course, our body doesn’t like this because losing muscle mass is a threat to our physical ability and overall health, and our body has no idea how long this reduced calorie intake will last.
To prevent us from losing excessive muscle mass, the body enters a biological state known as ‘ketosis’ where it starts using ketones (fats) for energy rather than glucose. This metabolic state means that the body no longer needs to derive its energy from muscle stores and instead burns fat (4).
However, we can also enter this fat-burning state without starving – by limiting our carbohydrate intake. In recent years, paleo, low-carb, and ketogenic dieters are all utilizing this method of burning fat by restricting the carbs they eat. If carbohydrate is low enough, then the body needs more energy than it is receiving – and in the absence of glucose, it starts burning fat for energy. In other words, you can eat a regular diet but still burn fat.
These diets are not for everyone, and there are positives, negatives, and myths regarding low carb diets. If interested in implementing one, the most important thing is to research properly and learn how to avoid the side effects.
Instead of drastically cutting calories, an exercise program can really help with weight loss in two different ways.
First of all, we can drastically increase our basal metabolic rate by engaging in intense exercise.
On the positive side, we can do this just by lifting heavy weights for a short duration. Squats and especially deadlifts are two of the best exercises for this purpose as they work almost every muscle in the body.
If you’re not quite ready for the gym and lifting weights, then even bodyweight exercises at home can make a big difference. Bodyweight squats, push-ups, and pull-ups are all excellent exercises.
The bonus is that these kinds of activities don’t just raise your BMR while you exercise – strength-based workouts leave your BMI high for long after you’ve finished exercising. In fact, research suggests that this boost in basal metabolic rate remains for up to 39 hours (5)!
Despite the benefits of resistance training, the most common activity we see for ‘fat burning’ is people running for an hour or two every day.
While all exercise is generally positive, the effect of this kind of cardio comes nowhere near strength training. Cardio does raise our metabolic rate while we exercise, but it soon returns to its regular rate after we finish.
Exercise also helps build more muscle, and higher muscle mass has the added benefit of increasing the metabolic rate.
3. Eating More Protein
The three macronutrients-carbohydrate, fat, and protein-all have very different biochemical impacts on the body.
However, out of all three macronutrients protein has the most significant impact on several key factors relating to weight loss;
- Muscle protein synthesis
Satiety is relatively self-explanatory; foods containing high amounts of protein leave us feeling full for longer and discourage food cravings between meals.
Thermogenesis refers to the heat generation caused by digesting and metabolizing food. Alongside our basal metabolic rate, it is one of the key factors that determine our energy expenditure throughout the day.
High thermogenesis means a higher rate of burning fat.
Lastly, muscle protein synthesis refers to how our bodies rebuild muscle.
For this to occur, we need to have a higher intake of dietary protein than the rate at which we are breaking our muscles down. For example, this means that those who are doing intense exercise will need a higher daily protein intake. If dietary protein intake is sufficient, then muscle growth will take place.
More protein means more muscle and more muscle means a higher metabolic rate and easier fat loss.
If we try to keep our calorie intake too low for too long, then the rate at which we burn energy slows.
This is a protective mechanism that helps us survive in times of starvation, and neurons in our brain activate it.
It makes a lot of sense, and it shows why we shouldn’t starve ourselves to try and lose fat.
At the end of the day, weight loss requires a sustainable lifestyle that we enjoy – not occasional crash diets to make up for a poor way of life.
These are the most crucial elements of a healthy lifestyle, and they are much more effective than crash dieting ever will be.
- NOW AND THEN: The Global Nutrition Transition: The Pandemic of Obesity in Developing Countries https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257829
- mTORC1 in AGRP neurons integrates exteroceptive and interoceptive food-related cues in the modulation of adaptive energy expenditure in mice http://dx.doi.org/10.7554/eLife.22848
- Fasting for weight loss: an effective strategy or latest dieting trend? http://www.nature.com/ijo/journal/v39/n5/full/ijo2014214a.html
- Low-Carbohydrate Nutrition and Metabolism http://ajcn.nutrition.org/content/86/2/276.full
- Effect of Resistance Training on Resting Metabolic Rate
- Effect on Nitrogen Balance, Thermogenesis, Body Composition, Satiety, and Circulating Branched Chain Amino Acid Levels https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5153533/
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